Gun order computer



Nov. 20, 1962 G. A. cRowTHr-:R E-rAL GUN ORDER COMPUTER Filed NOV. 12,1957 6 SheetS-She 650,965 A (eau/THE@ .4 WE1-'N65 S BROWN M//LL/AMdAMPro/v SYM' M 1TORNEY Nov. zo, 1962 Filed NOV. l2, 1957 6 Sheets-Sheet3 L7 5*'38 CAL. 2500 Fslv 3" 5o LAL. 2650 Fsw La "5 TRUEvALUE-DETERMlNED FROM I 4 BALLlsTnc TABLES MEcHANnzED VALUE l 3 IIIATf|h= f (Tf5)+.o443 Tfs- .1368

f"(rf5)= .ozge(ffs-3) I.2 FORTf5 3 5.25

.1096(Tf5 1.64) 1.10- FoR ;Tfs .5. 25

= .2|92(Tf5e.32)

FoR Tf5 8 L00' u) Y y 3.

o W g E2=zo .9o u IJJ .ao Hf E2 0 .6o ATfn .o I l I/ I I. I I I I I I ll I- V Y. JO

l l l l l I I l 0 l 2 3 4 5 6 7 8 9 l0 Il l2 I3 I4 5" TmE oF FL|G.HTsEcoNDs lNvENoRs 5y MW' ATTORNEY Nov. 20, 1962 G. A. cRowTHl-:R ETAL3,064,884

GUN ORDER COMPUTER 6 Sheets-Shea?l 4 Filed Nov. l2, 195'? NN www RWOP Yooe mi; m ci m mAa, A MM @em www., WM

Nov. 20, 1962 Filed Nov. l2, 1957 G. A. CROWTHER ETAL GUN ORDER COMPUTER6 Sheets-Sheet 5 L A wRE/vcf S. 3190 rwv W//L z. MM Q. HAM/P TOM BY MHD/ATTORNEY United States Patent O 3,064,884 GUN ORDER COMPUTER George A.Crowther, Lawrence S. Brown, and William G. Hampton, Long Island City,N.Y., assignors to Sperry Rand Corporation, Ford Instrument CompanyDivision, Long Island City, NX., a corporation of Delaware Filed Nov.12, 1957, Ser. No. 697,306 2 Claims. (Cl. 23S-61.5)

The present invention relates to an apparatus for converting gun ordersderived from the output of the gunre control computer of a "-38 cal. gunto corresponding gun orders for a 3-50 cal. gun.

In certain types of naval glmiire controls, a gun is controlled on themoving ship from a director which maintains -its sights on the target.Various data obtained by the director and from other sources areprocessed through a computer to `obtain orders for the proper tiring ofthe gun. Two of the primary `gun orders derived from the computer arethe gun elevation order angle Eg which is the ordered angle between theline of bore and its projection on the deck plane and the gun trainorder angle Bgr, which is the ordered angle between the vertical .planethrough the ships centerline and the vertical plane through the gun boreaxis, measured in the deck plane clockwise from the bow. These orderstransmitted to the guns are employed to direct the guns for propertiring.

One object of the present invention is to provide a comparatively simpleapparatus for converting the order angles E'g and B'gr derived from theoutput of the computer of the guniire control system of a 5-38 cal. gunto the corresponding gun orders for a 3-50 cal. gun thereby avoiding therequirement of a separate complicated computer for the 3-50 cal. gun. Acomputer for the gun lire control system of a 5"-38 cal. gun is ComputerMark 1A Model 13. The converter embodying this invention does not affectthe regular operation of the Computer Mark 1A in its solution of the5-38 cal. gun problem.

In accordance with the present invention, increments of gun elevationand gun train respectively are computed by the converter of the presentinvention to be added to the 5"-38 cal. gun `orders calculated in theknown manner in a compuer to produce corresponding gun orders for the3-50 cal. guns. These increments are computed as functions of either the350 cal. time of flight or the 5"-38 cal. time of Iilight. Straight lineapproximations are used extensively in the derivation of the formulaswhich are the basis of the mechanization. A high degree of correction isavoided to maintain simplicity, minimize the size of the convertermechanism and reduce the 'amount of components to a minimum.

GLOSSARY OF SYMBOLS S-pertaining to 3"-50 cal. gun.

5-pertaining t-o 5"-38 cal. gun.

A-inerement between 3 and 5" values.

Bgr-gun train orderthe angle between the vertical plane through theships centerline and the vertical plane through the gun axis measured inthe deck plane clockwise from the bow.

IR-rate of change of range.

)E2-predicted target elevation or ballistic position anglethe anglebetween the horizontal plane and the line of re to the future targetposition, measured upward from the horizontal plane.

Alib-director elevation angle-the angle between the deck plane and theline of sight measured in the vertical plane through the line of sightupward yfrom the deck plane.

3,064,884 Patented Nov. 20, 1962 ICC Eg-gun elevation order angle-theangle between the deck plane and the line of tire, measured in thevertical plane through the line of tire. Positive angles are measuredupward from the deck plane.

AIV-change in initial velocity from normal value (value before gun hasbeen tired) L-level angle-the angle between the deck plane and thehorizontal plane measured in the vertical plane through the line ofsight-positive when the portion of the deck towards the target is down.

RdB-linear elevation rate (knots)-the component of relative velocity ofship and target which is at right angles to the line of sight in thevertical plane containing the line of sight (positive when upward).

RdBs-linear Abearing ratethe horizontal component of relative velocityof ship and target which is at right angles to the vertical planecontaining the line of sightpositive to the right.

Tf-time of flight-the time of flight of the projectile to the predictedor future target position.

ATfn-normal ditierence between Tf3 and TfS.

ATm-tirne of flight increment, correction for the time of ight due todiierence between the actual velocities of the 5 gun and the 3 gun.

Tf/RZ-conversion constant (sec./yd.).

Vfn-normal sight angle-the difference between normal gun elevation orderangle and director elevation angle.

Vinsight angle correction due to change in initial velocity.

Vt-sight angle correct-ion (deg.) due to elevation rate RdE.

Zd-crosslevel angle-the angle between the vertical plane through theline of sight and the plane perpendicular to the deck plane through theintersection of the deck plane and the vertical plane through the lineof sight.

Various other objects, features and advantages of the invention areapparent from the following description and Ifrom the accompanyingdrawings, in which FIG. l is a graph showing in `full lines the truevalues derived from the ballistic tables and in dotted lines the assumedvalues for mechanization of the AVm corrections to 3-5G cal. sight anglefor loss of IV at different values of Tf3 for dilerent position anglesE2;

FIG. 2 is a graph showing in full lines the true values derived from theballistic tables and in dotted lines the assumed values formechanization of the AVfn sight angle correction under normal initialvelocity conditions at diierent values of Ty5 `for dilerent positionangles E2;

FIG. 3 is a graph showing in full lines the true values derived from theballistic tables and in dotted lines the assumed values formechanization of ATfn at dilerent values of Tf5 for different positionangles E2;

FIG. 4 is a graph showing in full lines the true values derived from theballistic tables and in dotted lines the assumed values y:formechanization of ATm corrections to T f for FSIV loss at differentvalues of Tf for diierent position angles E2;

FIG, 5 is a graph showing in full lines the true values derived from theAballistic tables and in dotted lines the assumed values formechanization of Tf3/R2 for position tangle E2 of 45 at dierent valuesof Tf3; and

FIG. 6 is a diagram of a mechanism for obtaining the elevation orderangle E'g and the gun train order angle Bgr.

Derivation of Formulas The difference between the 5 elevation orderangle EgS and the 3" elevation order tangle -Eg3, which is also thedifference between the 5" sight angle Vs5 and the 3" sight angle VS3,designated as AEg is composed of the difference AVm in superelevation orsight angle correction due to either the 3 or 5" initial velocity notbeing normal, the difference AVfn in superelevation or sight anglecorrection under normal initial velocity conditions and the dierence AVtin superelevation or sight angle correction for the elevation rate oftarget motion during the interval of ATf/RZ. The basic equation to bemechanized designating this relationship is as follows:

The normal initial projectile velocity is the velocity of a projectileof a gun fired for the iirst time and this velocity designated as f.s.(feet/sec.) is determined from the usual available ballistic tables forthe gun. These tables indicate that the normal initial velocity of a5-.38 cal. gun is 2.500 f.s. and of a 3.50 cal. gun is 2650 f.s. As thegun is fired, it loses initial velocity.

AVm is the difference in correction due to either the 3" or 5" initialvelocity being other than normal and is shown in the graph of FIG. 1.The differences in correction to sight angle between the 3" ballisticsand the 5" ballistics are so slight that they may be considered equal.As shown in the graph of FIG. 1 and as determined empirically therefrom.

Substituting in Equation 2 for AIVS and AIVS their respective equals,l-(2600-IV5) and l00-(2750-1I/3), there is obtained AVm=.00041Tf3 cos(E24-L) [100-(2600IV5) \(100l-2750-IV3)] AVm=.00041Tf3 cos (E24-L)[(2750-IV3) (2600-11/5 The true values of AVfn determined from tbeballistic tables and the values approximated therefrom for easymechanization are plotted in FIG. 2 as functions of AVfn cos E 2+14 inorder to minimize the effect of the position angle E2.

The best mechanical solution is obtained by mechanizing the equationAVfn=f(Tfn) where AVfno is the normal correction sight angle at 0elevation angle E2. Since this expression is a function of 5" normaltime of flight, it is affected by changes in the 5" initial velocity andmust be corrected. Accordingly,

AVfno=k(fTf5-}.0O03 65 TSAI V5 In the latter equation, k is not aconstant but Varies. However, for the purposes of 5" correction, anaverage value of .175 is chosen and for AIVS is substituted its equal100-(2600-11/5). Then AVfno=k(fTf)5+.O0639Tf5-.0000639Tf5 (Z600-ZVS) (4)In instrumentation, the product of Tf5 and IVS must be tion. Since theproduct of Tf3 and IVS is employed in connection with other phases ofinstrumentation herein, aS will be described, for the term.0000639Tf5(2600-IV5) in Equation 4, there is substituted .0000639Tf3(Z600-1F75 to avoid the necessity of an additional amplifying step. Thediierence between the values of the two terms is insignificant.

The best average solution for AVfn is obtained by subtracting a constantfrom AVfno AVfn: (AVfno-.24) cos (E2-I-L) AVfn: [f (TfS -l-.00639Tf5.0000639Tf3 (Z600-ZVS) .24] cos (EZ-l-L) Referring to FIG. 2, it shouldbe noted that the mean average represented by the graph A actuallymechanized by the instrumentation of the present invention is offset bythe constant vertical increment .Z4-.14. This graph A is the mean`average of the two graphs for E2=O and E2=70.

The values of 3'(Tf5 in Equation 5 for different values of Tf5 areindicated in FIG. 2 as determined empirically from the graph therein.

The only other correction to sight angle is AVt, the correction for theelevation rate of target motion during the interval of ATf/RZ.

AVt=lcRdE -l2f radians RdE is measured in knots ATf q 1s measured 1nee/yards k=.563 yd./sec./knot of target speed 57.2958/radian k=32.26

en AVIS-32.26RdEX R2 (6) To determine the quantity ATi/R2 in Equation 6,the true and mechanized values of T f/R2 are plotted against the 3" timeof iight in lFIG. 5. Since there is no appreciable change in Tf/RZ forvarious position angles E2 and being average, the values are plottedonly for 45 position angle. Since the predicted values of the 5 inch guncomputer are based on the 5"Tf/R2, it is necessary to correct only forthe difference between the 3"Tf/R2 and the 5Tf/R2. 'I'his increment ofTf/RZ is equal to ATf/R2=.001110+.oooo6s5rf3 +.ooo0ooe(275o-IV3 (6a)Both the quantity Tfs Rz i and the quantity rfa have the constant.001110 as a common reference. The constant .001110, therefore, may beeliminated from equation 6a in mechanizing said equation, assuming thatthe input has had this constant eliminated.

In Equations 3 and 5, the term Tf3 is involved and, therefore, it isnecessary to determine the value of this amplified before being utilizedfor further instrumenta- 75 term for mechanization.

5 It is known that Tf3= TS +A'Tfn-l-ATm-i-.001126dRUf3 TfS) (7)(Ignoring corrections for wind, air temperature and air density) ATfn isthe difference between the normal 3" time of ight and the normal 5 timeof ight and is plotted on the graph of FIG. 3 as a function of the 5"time of flight. From the ballistic tables, the two true value curves forE2=0 and E2=70 indicated in full lines are plotted, and from these twocurves, the true value curve representing the mean value of ATfn foundto approximate that for au E2=30 is plotted in full lines. From thelatter true value curve, the mechanism curve B made up of straight linesis approximated therefrom and this is used to determine the approximateempirical formula used as a basis of instrumentation. Hence:

ATm is the correction for the time of ight due to difference between theactual initial velocities of the 5" gun and the 3 gun. The LV.corrections have been plotted in FIG. 4 together with the mechanismvalues for both the 5" and 3 gun. The 5" LV. correction is notcoincident with the theoretical value as shown by the curve C, andmechanization for ATm is, therefore, preferably along said curve, asindicated by the curve D.

Hence, as determined empirically from the graph of FIG. 4

ATm=.000365Tf5AI V5 -.000525T f3AI V3 Since TIS usually is very nearlyequal to TB, then ATm=.000365Tf3Al V5 -.000=525T J3Al V3 where AIV isconsidered positive for increasing IV. Substituting Tf?) for Tf5 willcause a maximum error of .07 second.

`Correction for the change in range during the time of Hight isexpressed in Equation 7 as .001126dR(Tf3-Tf5), since the 5" time offlight is predicted on the 5" advance range R2. This leaves only thedifference between the 3 and the 5" time of i'lig tto be corrected. Theconstant .001126 is the average Tf/R2=.002 sec./yd. 563 yd./ sec/knot oftarget speed. An assumption of a fixed dR rate, equal to approximately450 knots, further simplies the mechanization, so that Equation 7 may bere- Referring the I.V. scale to 2600 f s. for IVS and 2750 f s. for IV3,for convenience in mechanization as indicated above in connection withother phases of the mechanization, Equation 11 may be rewritten bysubstituting for AIVS its equal (l-AIV5) when referred to 2600 f.s. andfor AIV3 its equal (100-AIV3) when referred to 2750 f.s. Therefore,

AIV3 (2750-1V3) A'IV5= (2600-1V5) Rewriting Equation 11 with thesubstitutions indicated, there is obtained 1.0293Tf .0919 -I- .662f (Tf)1 .0106- .000348(2750 IV3) -I- 000242 (2600 Il/'5) (12) The value of f'TfS) is indicated in FIG. 3 for different values of Tf5.

The only corrections to gun train orders B'gr are for 1) Component oftarget motion perpendicular to line of sight during the differencebetween the 3Tf and the 5"1`f.

(2) A Dzs correction in the deck plane for trunnion tilt. The resultantbearing rate due to target and ships motion is called RdBs and istransmitted from the computer of the 5 gun. This bearing rate whenmultiplied by ATf/RZ gives the predicted increment of gun train whenmultiplied by the proper conversion constants and results in thefollowing equation No correction AVz, i.e. difference in correction togun elevation to compensate for trunnion tilt, is made to the gunelevation order increment AE'g, since it is assumed that the correctionsupplied by the computer of the 5" gun to its computed gun elevation issuicient. The converter of the present invention does supply a gun trainorder correction, which is an approximation of the solution of the 5"gun computer, this solution being represented as follows:

Since the inputs to the converter are 5"Eg and 5Bgr, these -do containthe trunnion tilt corrections. This results in the equation ADzs=1.22sin ZdAEg Substituting Equation 14 in Equation 13 results inABgr=[32.26RdBSX ATf/RZ The f(Tf5) in Equation 12 is determinedempirically for the different values of TfS from the graph of FIG. 3 andthese values are as follows:

f"(Tf5)=.029e(Tf5-3) for Tf5 3 5.25

=.1096(Tf54.64) for Tf5 5.25 8 \=.2192(Tf5-6.32) for Tf5 8 The y(Tf5) inEquation 5 is determined empirically for the different values of Tf5from the graph of FIG. 2 and these values are as follows:

f"(Tf5)=.027(Tf5-3) for Tf5 3 5.25

y=.100(Tf5-4.64) for Tf5 5.25 8 l=.200(Tf5-6.32) for Tf5 8 ATf/RZ forEquation 6 is as follows: ATf/R2=.001110-1-.0000665Tf3+.0000006(27501V3) -TfS/RZ (6a) In Equation 6a the constant .001110 iseliminated, assuming that the input TfS/RZ has had this constanteliminated.

The equation for AB'gr is as follows:

FIG. 6 shows the mechanism for the instrumentation of Equations 1, 3, 6,12, 6a and 15 to obtain the values of E'g(3) and Blgr(3). The inputsnecessary to attain these values are (1) Tf(5) 5" time of flight.

(2) Tf5/R2 (3) I.V. (5") 5l initial velocity.

(4) RdBs Bearing rate.

(5) RdB Elevation rate.

(6) EZ-l-L Sum of elevation angle E2 and level angle L.

(7) Zd Cross-level angle.

(8) E'g(5) l5" gun elevation.

(9) B'gr(5") 5" gun train order.

(10) I.V. 3" 3" Initial velocity.

Inputs 1-9 are obtained from the output of the computer for the guniirecontrol system ofthe 5" gun. Input 10 determined from ballistic tablesis set by a handcrank 10 (FIG. 6) periodically, as for example, everyday, in accordance with the number of rounds of ammunition already firedfrom the 3" gun.

FIG. 6 shows diagrammatically the converter by which the gun elevationorder Eg and the gun train order Bgr for the 5" gun are converted intothe corresponding orders for the 3" gun. In this diagram of FIG. 6, thedotted lines represent mechanical motion transmissions and the fulllines represent electrical connections for transmitting electricalquantities. The mechanical motion transmitters may represent shafts, andthe values of the quantities transmitted thereby are represented by thenumber of revolutions of these shafts. The electrical connectionstransmit currents, the voltages of which correspond to the values of thequantities transmitted.

The system of FIG. 6 is composed of components, such as resolvers,potentiometers, adding networks and servo mechanisms, which, per se, arewell known. These, therefore, are shown only schematically and referredto brieliy.

Tf3 is one of the essential quantities required` to evaluate the 3" gunorders, and is determined from Equation 12. For the solution of thisEquation 12, there are required inputs Tf5, IV3 and TV5, and thedetermination of f"(Tf5). As indicated in the graph of FIG. 3, thevalues of f"'(Tf5) vary according to the values of Tf5. A potentiometer11 with a mechanical input Tf5 derived from the output of the 5"computer is wound to incorporate therein the values of "'(Tf5) for thedifferent values of Tf5 according to the graph of FIG. 3, so that theoutput of this potentiometer will be a voltage corresponding to f"(Tf5).This quantity f"(T;f5) is then transmitted to a resistor adding network12, the output of which is -Tf3 constituting the algebraic sum of theinputs according to Equation l2. An adding network capableroffunctioning according to the foregoing requirement is described in theJune 1947 issue of the publication entitled Electronic Engineering onpages 178-180 thereof. A high gain linear amplifier 13 for the output ofthe adding network 12 provides power amplification which serves toisolate the signal source and load impedance. Since the output of thenetwork and amplilier combination 12 and 13 has a 180 degree phase shiftfrom the signal input, it

is also used for the purposes of obtaining this phase shift in order toprovide means for algebraic addition.

The quantity -Tf3 obtained as described, is converted into -l-Tf3 by anetwork 14 and amplified in the amplifier 15, for the purpose to bedescribed.

A further input into the adding network 12 is the electrical quantityTf5. Since this quantity is available from the computer of the 5" gun asa mechanical quantity, this quantity is converted into an electricalquantity by a potentiometer 16 for transmission to the adding network12.

Another input into the adding network 12 is the quantity Tf3 IV3. Forobtaining this quantity, the crank 10 is set periodically, as forexample, each day according to the value of IV3 obtained from theballistic tables for the number of rounds of ammunition already tired.This quantity IV3 so obtained is fed as a mechanical quantity into apotentiometer 17 having as an electrical input the quantity Tf?,obtained as described from the output of the combination 14, 15. Theelectrical output Tf3 lV3 obtained thereby from the potentiometer is fedas an input into the adding network 12.

Another input into the adding network 12 is the quantity -TJB XI V5. Forthat purpose, the electrical quantity -Tf3 from the unit 12, 13 istransmitted to a potentiometer 18 receiving also the mechanical inputIVS, to produce the electrical output -TSXIVS which is transmitted tothe adding network 12 as an input.

The input quantities -Tf3XIV5, f"(Tf5), TS, Tf3 lV3 and ,-Tf (feedbackfrom the output of the amplifier 13), when multiplied by the appropriatecoeflcients and combined with the appropriate constants in the addingnetwork 12 in accordance with Equation 12 are algebraically added toproduce the quantity -Tf3.

The quantity to be determined in the mechanization of Equation 1 isAVm-l-AVJn. One of the quantities necessary to obtain this sum of AVmand AVfn is f" (Tf5) as indicated in Equation 5. The value of 1"(Tf5) isindicated in the graph of FIG. 2 for the different values of Tf5. Thisquantity f"(Tf5) has an approximately constant relationship to thequantity "(Tf5) obtained from the potentiometer 11, and the electricaloutput hom this potentiometer may be multiplied by a constant in amultiplying network 20 to obtain the quantity J(Tf5) as shown, or ifdesired, another potentiometer with the windings arranged in accordancewith the relationship f"(Tf5) may be provided to obtain the electricalquantity f(Tf5). This quantity f(T]5) so obtained is transmitted to anadding network 21 as an input.

Other inputs into the adding network 21 are the electrical quantity Tf5obtained from the output of the potentiometer 16 and the quantity -Tf3Xl V5 obtained from the output of the potentiometers 18.

The three inputs Tf5, f(Tf5) and -Tf3 lV5, com. bined with appropriatecoefiicients and constants in accordance with Equations 3 and 5 in theadding network 21 result in the electrical quantity AVfn-i-AVm cos(E24-L) which is amplied by the amplifier 22. This amplified electricalquantity is transmitted to a resolver 23 as an input in conjunction withthe mechanical quantity E2+L obtained for the computer of the 5" gun.The resolver 23 produces cos (EZ-l-L) and has a potentiometer ormultiplier therein to multiply this quantity by the quantity AVfn-l-AVmcos (E24-L) to obtain the electrical output AVfn-I-AVm. 'This electricaloutput is transmitted to an adding network 24 as an input.

The other input into the adding network 24 is the quantity AVt. Toobtain this quantity AVt, it is necessary to determine the quantityATf/RZ in accordance with Equations 6 and 6a. The quantity TS/RZ inelectrical form for the purpose, is obtained from a potentiometer 26having TfS/RZ as a mechanical input obtained from the computer of thegun. The electrical quantity TfS/RZ so obtained is transmitted as aninput to an adding network 27, which also receives as inputs thequantities -Tf3 and IV3 and also the feedback ATf/RZ from the output ofan amplifier 28, the electrical quantity IV3 coming from a potentiometer29 with a mechanical input IV3 from the crank 10. The constants andcoeiiicients in accordance with the Equation 6a built into the addingnetwork 27 result in the quantity ATJ/ R2. This quantity amplified bythe amplifier 28 is transmitted to a potentiometer 30.

The positive quantity ATf/RZ is converted into the correspondingnegative quantity by a network 31 and amplilied by the unit 32. Thenegative output is transmitted to the potentiometer 30 in conjunctionwith the corresponding positive quantity, since the output may be eithernegative or positive. The mechanical input RdE from the computer of the5" gun into the potentiometer 30 results in the electrical output AVt,which is transmitted to the adding network 24 in conjunction with thequantity AVm-l-AVfn to produce the electrical output quantity AEg inaccordance with Equation l. The electrical output quantity from thisadding network 24 is processed through a servo mechanism 32 to obtain thcorresponding quantity in mechanical form -to be added to the 5" gunelevation order for transmission as a 3" gun elevation order. This servomechanism 32 is of well known type and constitutes in effect anautomotive drive which positions a mechanical load in accuratecorrespondence with an input without placing an appreciable load uponthis input. The basic components of the servo mechanism 32 comprise aservo control 33, a servo amplifier 34, a servo motor 35 and aninduction generator 36, all connected in a double loop circuit with theadding network 24. Essentially, the adding network 24 computes a voltageproportional to the error between a function of the input and a functionof the output. This error voltage is converted to a frequency of 60cycles by the servo control 33, amplified by the servo amplifier 34 andsupplied to the servo motor 35 for its control. The servo motor 35furnishes the mechanical output and drives the induction generator 36.From this induction generator 36, a voltage proportional to the outputvelocity is supplied to the servo control 33. After being modified bycomputing elements in the servo control 33, the modiliedvoltage iscombined Iwith the error voltage to improve the operation of the servomechamsm.

The output of the servo motor 35 is the mechanical quantity AEg and isbranched olf to a potentiometer 37 to be converted into thecorresponding electrical quantity for feedback into the adding network,and is also branched olf to a summing transmitter 40 to be added to the5" gun elevation order E'gS for the production of the 3 gun elevationorder EgS and for the transmission thereof to the 3 gun control.

The transmitter 40 is of the type well-known in the gunre controlsystems and comprises essentially of a fine differential synchro 41 anda course differential synchro 42 operated from the quantities AEg andEgS and corrected cal quantity sin Zd. These quantities required inopposite phases because the AE'g may be positive or negative andtransmitted as inputs to a potentiometer 47 in conjunction with themechanical input AE'g, result in the electrical quantity AEgXsin Zd.This latter quantity is transmitted as an input to an adding network 48.

Also transmitted to the adding network 4S is the electrical quantityRdBsXATf/RZ obtained from the output of a potentiometer 49 having asmechanical input the quantity RdBs obtained from the 5" gun computer,and the electrical inputs -ATf/RZ and -I-AT/RZ obtained in the mannerdescribed. A further electrical input into the adding network 48 is thequantity AB'grXcos (E4-L). The quantity AB'gr obtained as a mechanicalfeedback from the output of a servo mechanism Sil arranged inconjunction with the adding network 48 for 4the purpose described inconnection with the adding network 24 and the servo mechanism 32, istransmitted as an input to a potentiometer 51 in conjunction with thepositive quantity cos (E24-L) obtained from resolver 52 and the negativequantity -cos (E24-L) obtained from the resolver 53. The resultingelectrical output A'BgrXcos (E24-L) which may be negative or positive istransmitted -to the adding network 48.

The inputs AEgXsin Zd, RdBsXATf/RZ and ABgr Xcos (E2-FL) into the addingnetwork 48 combined with the appropriate parameters in accordance 'withEquation l5 result in the electrical output ABgr which is processedthrough the servo mechanism 50 and converted into the correspondingmechanical quantity. The adding network 48 may be arranged in similarmanner to adding network 12 referred to above. This mechanical quantityABgr added to the mechanical quantity Bgr5 from the 5" gun computer in asumming transmitter 54 similar to the surnming -transmitter I40, resultsin the gun train order Bgr3 for the 3 gun. This gun order Bgr3 istransmitted for the control of the 3" gun.

Also necessary for the 3" gun control is the parallax correction Phwhich is the train parallax correction for a horizontal base. A synchrotransmitter system with the Ph from the 5 gun computer as an input maybe provided to transmit parallax correction for the horizontal distancebetween the director of the gunfire control system of the 5" gun and the3 gun mount.

What is claimed is:

l. A converter for converting the gun elevation order angle Eg of thecomputer of the gunlire control of a "-38 cal. gun to the correspondinggun order for a 3"-50 cal. gun, comprising means for receiving signalscorresponding in magnitude to the respective quantities TfS-time ofprojectile ight to target from 5 gun Tf5/R2-the ratio of time ofprojectile iiight from 5" gun to the advance range of the targetIV5-initia1 projective velocity from the 5" gun RdB-elevation rate whichis the component of relative velocity of the ship on which the 5" and 3"guns are disposed and the target which is at right angles to the line ofsight in the vertical plane containing the line of sight Cos (E2+L)-cosine of predicted target elevation angle E2 from the ships deckplane on which the 5" gun is mounted plus level angle L Sin Zd-sine ofcross-level angle which is the angle between the vertical plane throughthe line of sight and the plane perpendicular to the deck plane throughthe intersection of the deck plane and the vertical plane through theline of sight IV3-initial velocity of 3" gun E'gS--gun elevation orderangle of the 5" gun, means responsive to the input signals Tf5, IVS andIV 3 and to a signal corresponding in magnitude to the quantity f'"(TJS) for mechanizing the equation wherein T f3=time of projectile ightto target from the 3" gun for obtaining a signal corresponding to thequantity Tf3, means for employing the input signals cos (E24-L), 1V3 andIVS, the signal Tf3 and a signal corresponding in magnitude to thesignal J"(Tf) to mechanize and solve the equations A is incrementbetween gun order values for the 3" and 5" guns Vm is the sight anglecorrection in gun elevation order angle due to change in initialvelocity from 5" gun to 3" gun Vfn is the normal sight angle which isthe dierence between normal gun elevation order angle and directorelevation angle and for obtaining the signal AVm-l-Afn, means responsiveto input signals IV3 and TfS/RZ and the signal Tf3 for mechanizing theequation ATf/R2=.0000665Tf3-l-.0000006(2750 -lV3)-Tf5/R2 wherein T f/RZis the ratio of the time of ight of the projectile to the projectiletarget position to the advance range to the predicted target positionand constitutes a conversion subtractor to obtain the signalcorresponding in magnitude to the quantity ATf/RZ, means responsive tothe input signal RdB and the signal ATf/RZ for mechanizing the equationAVt=32.26RdEXATf/R2 wherein Vt is the sight angle correction due toelevation rate Rde to obtain the signal corresponding in magnitude tothe quantity AVt, means for adding the signal AVm-l-Afn and the signalAVt in accordance with the equation RdBs-bearing rate of ship on whichthe 5 "-38 cal. gun

and the 3-50 cal. gun are mounted and target Sin Zd-sine of cross-levelangle, means responsive to the signals RdBs, sin Zd, AT f/R2, cos(E24-L) and AEg for obtaining a signal corresponding in magnitude to thetrain order angle quantity AB'gr in accordance with the relationshipABgr=[32.26RdBsXATf/R2 l +1.22 sin ZdAE' g] -cos (E2+L) and means foradding the signal AB'gr to a signal B'gr corresponding in magnitude to-the train order angle for the 5 gun to produce the train order anglefor the 3" gun and for transmitting the latter order angle for controlof the 3" gun.

References Cited in the le of this patent UNITED STATES PATENTS2,434,274 Lakatos Ian. 13, 1948 2,670,134 Lakatos Feb. 23, 19542,766,934 Sigley et al. Oct. 16, 1956

